Land Below3 books in series
The Land Below Publisher's Summary
A treasure hunt into the deepest cave system in Europe takes a turn for the worst. Now, rather than treasure, it is survival that is at the forefront of the spelunkers' thoughts. But their attempt to escape out of the dark deep places is thwarted. Men are not at home in the depths. But there are things that are... pale terrifying things. Huge things. Things red in tooth and claw.